DreamHost, one of the world’s largest web hosting companies, said a distributed denial-of-service (DDoS) caused significant outages Thursday affecting customers of its web and email services.

The Los Angeles-based hosting provider said that “internet vigilantes” conducted an attack against part of its online infrastructure resulting in connectivity issues affecting several aspects of its operations, ranging from its online customer support features to the hosting service used by over 1.5 million websites.

The attack targeted DreamHost’s Domain Name Servers (DNS) – digital directories that allow internet users to access specific websites without remembering their lengthy, numeric IP addresses – and was remedied about four hours after first being detected, according to the company.

Low-level attacks are capable of briefly disabling websites lacking DDoS protection, but wide-scale attacks like the one conducted last year against Dyn, an American DNS provider, caused unprecedented outages affecting some of the world’s most popular websites, including Amazon and Netflix.

DreamHost customers, including the Cambridge Seventh-day Adventist Church in England and the Tale of Two Wastelands video gaming project, were among those who said their websites were unavailable Thursday due to the powerful DDoS attack.

The DDoS attack was confirmed by DreamHost as two of the company’s customers made headlines in their own right over their unrelated efforts to survive scrutiny: DisruptJ20, an anti-Trump protest site, and The Daily Stormer, a white supremacist website that remerged online this week with the help of DreamHost after being all but driven off the internet.

A federal judge earlier Thursday ordered DreamHost to provide information sought by federal prosectors investigating the riots that erupted in Washington, D.C. during President Trump’s inauguration Jan. 20. The Daily Stormer, meanwhile, relaunched on a DreamHost website Thursday after previously being banned from the internet’s biggest domain registrars and hosting providers, including GoDaddy, Google and Cloudflare.

The Daily Stormer had quietly registered the new domain using an automated signup form and was subsequently booted several hours later, , DreamHot said Thursday evening.

“Unfortunately, determined internet vigilantes weren’t willing to wait for us to take that action,” DreamHost said in a statement to Ars Technica. “They instead launched a DDoS attack against all of DreamHost this morning. We were ultimately able to declaw that attack, but the end result was that most of our customers experienced intermittent connectivity issues to their sites today.”